Lightweight Ti–Zr–Be–Al bulk metallic glasses with improved glass-forming ability and compressive plasticity

A series of lightweight Ti–Zr–Be–Al bulk metallic glasses (BMGs) have been developed through the addition of Al to Ti–Zr–Be ternary glassy alloy. By replacing Be with Al, the critical size of the glassy rod has been increased from 5 mm for Ti41Zr25Be34 alloy to 7 mm for Ti41Zr25Be29Al5 alloy, while the yield strength of Ti41Zr25Be34 − xAlx (x = 2–10) has been greatly enhanced, resulting in a significant increase of the specific strength which is defined as yield strength/density. Among these newly developed Ti–Zr–Be–Al BMGs, Ti41Zr25Be26Al8 glassy alloy exhibits a high specific strength of 4.33 × 105 Nm/kg and a very large compressive plastic strain of 47.0%, which are much larger than those (3.69 × 105 Nm/kg and 2.9%, respectively) for Ti41Zr25Be34 glassy alloy. The present results show that Al is an effective alloying element for improving the glass-forming ability (GFA) and mechanical properties of Ti-Zr-Be glassy alloy.